Projectors are well known that modulate light beams emitted from a light source in accordance with image information and project it on an enlarged scale. Such projectors are used for various applications: presentations with personal computers in companies, movie viewing at home, and so on.
Such projectors include an optical system for forming an optical image, a light source, a supply circuit for supplying them with power, a lamp drive circuit, and a casing for accommodating them.
The light source, the supply circuit, and the lamp drive circuit are heat sources that generate heat in operation, whereas optical components and optical modulators of the optical system include heat-sensitive ones. Therefore, the projectors are provided with a cooling system that takes in cooling air from the exterior of the casing to cool the components in the casing.
The cooling system is classified into an optical-system cooling system, a light-source cooling system, a power-supply and lamp-drive-circuit cooling system, and employs the following structure:
For example, the optical-system cooling system has a discharge fan near a discharge port of the casing and exhausts air that cooled an optical system with the discharge fan, as described in JP-A-2000-330202 (FIGS. 7 and 8) and JP-A-2000-10191 (FIG. 1). The light-source cooling system lets the air that has cooled the optical system into a light source and then discharges it with the discharge fan. The power-supply and lamp-drive-circuit cooling system lets the air that has cooled the optical system into a power supply and a lamp drive circuit to cool them and then exhausts it with the discharge fan.